The present invention relates generally to the field of tripod supports, and is specifically designed to provide a connecting bracket for a low cost tripod support for an engine-lifting winch.
In general, due to the current high cost of professional automobile maintenance, many car owners have become "home mechanics" who make their own repairs. In order to effect such repairs, it is necessary from time to time for the home mechanic to completely remove the automobile engine from the chassis of the car. This is done in order to afford the repair person complete access to all parts of the engine. However, the typical home mechanic does not have facilities to complete such an engine-lifting operation. Thus, the home mechanic must either take his car to a professional repairman, or construct a crude engine-lifting structure out of the materials available to him. Typically, such home-made engine-lifting structures are highly unstable and dangerous. Accordingly, a need has developed for a suitable support structure for an engine-lifting mechanism such as a winch or other such device which can be used to lift heavy objects. Ideally, such a support would provide a stable mounting for the winch assembly, support the lifted engine during the lifting operation, and maintain the engine at a certain height above the ground while the mechanic effects his repairs.
Among the support structures developed in the prior art which are suitable for providing such a winch mechanism support is the common tripod. Tripod-like structures provide stable support for such mechanically sensitive (and relatively lightweight) devices as cameras and survey equipment. However, since the stability of a tripod is due to the fact that the weight of the supported device is evenly distributed between three ground-engaging legs, it would seem that a tripod-like structure would be an ideal support for an engine-lifting winch.
U.S. Pat. No. 737,765 (issued Sept. 1, 1903 to G. Olsen) discloses a grubbing (or winch) machine supported on such a tripod-like structure. In Olsen, two of the three tripod legs are mounted flush to a set of horizontal support plates, forming an "A" frame construction. The third leg is pivotally connected to the other two legs, and the planes of both the plates and the third leg are at acute angles with respect to the vertical plane of the earth. The grubbing machine is mounted between the support plates, and the grubbing line therefrom extends downward from the pivotal connection. The tripod support structure of Olsen possesses several disadvantages which render it impractical for use in the specific engine-lifting winch application of the present invention. The main disadvantage inherent in the tripod support structure of Olsen is that it is not collapsible. In other words, it is preferable that the tripod support be collapsible (or readily taken apart) in the manner of the common sawhorse which is constructed of a plurality of wooden planks interconnected by steel connecting brackets. The "unitary" construction of the Olsen tripod support makes it both too costly and too hard to store for the typical homeowner. Thus, it is desirable to provide a tripod support structure which has a connecting bracket for interconnecting the three legs of the tripod, such that the tripod may be readily taken apart and stored.
U.S. Pat. No. 3,779,497 (issued Dec. 18, 1973 to Webber) discloses a tripod and a clamp therefor in which the clamp comprises a plurality of cylindrical receptacles which are all angled both from the vertical and with respect to each other. The clamp comprises a triangularly shaped upper plate with a recess in its lower surface. A triangularly shaped lower plate is disposed within the recess of the upper plate. The corners of both the upper plate and the lower plate are provided with semi-cylindrical recesses into which the tripod legs are inserted. The plates are further provided with a centrally disposed screw-and-wing-nut arrangement which tightly secures the tripod legs within the cylindrical receptacles. The bottom portion of the screw comprises a vertical hook.
The connector construction of Webber presents several disadvantages in an engine-lifting winch application. Webber is chiefly concerned with providing a stable support, not above eye-level, for photographic mechanisms and would not be practicable for or capable of supporting substantial weight which is to be lifted a vertical distance of several feet. Another disadvantage of the tripod clamp as disclosed in Webber is that it comprises several parts - the triangularly-shaped upper plate, the eyebolt, the release spring, the collar or washer, the recess-engaging lower plate, and the wing nut. If any one of these several pieces is somehow lost or broken, the entire device is rendered inoperable.
Also, the tripod clamp as disclosed in Webber depends for rigidity and stability solely upon the limited clamping effect afforded by the threaded bolt and wing nut. It is further noted that another disadvantage of the Webber disclosure is that the wing nut must, to accomplish the desired clamping effect, draw the first and second members toward one another. The said drawing action of the wing nut is opposed and possibly jeopardized or reduced as soon as the load to be lifted becomes suspended from the hook or eye. Moreover, the tripod clamp as disclosed in Webber, owing to the plurality and complexity of its various constituent parts, is expensive to manufacture. Another disadvantage of the tripod clamp disclosed by Webber is that the practical length of the legs is quite limited owing to the necessity that the user have access to the several parts during assembly and for adjustment; thus, in an engine lifting application, for example, where the engine must be lifted several feet above the ground level, the wing nut would be well beyond the reach of the user. Accordingly, it would be advantageous to provide a unitary connecting bracket for a tripod support which is: adaptable to a large variety of leg diameters and lengths; easy and safe to erect and use owing to its integrated, one-piece construction, and; not dependent for its rigidity or stability, upon any clamp or clamping action.